飞机油箱用材7075铝合金在积水环境中的微生物腐蚀规律

Corrosive Behavior of 7075- T6 Aluminum Alloy as Plane Fuel Tank Material in Accumulative Water Environment

为了研究飞机油箱用材7075铝合金积水环境中微生物繁殖造成的腐蚀规律,以油水体系模拟腐蚀环境,测定了体系中硫酸盐还原菌(SRB)的生长曲线,采用金相分析、极化曲线、电化学阻抗谱等方法,研究了7075-T6铝合金的腐蚀形貌和电化学腐蚀行为。结果表明:在培养温度为30℃下,SRB可以在7075-T6铝合金表面附着、生长并形成不均匀的微生物膜;7075-T6铝合金腐蚀电流密度先增大后减小,与体系中SRB的数量变化规律一致,SRB代谢产生的腐蚀性阴离子S2-和SRB阴极去极化的协同作用,促进了7075-T6铝合金的腐蚀。

A jet fuel-water system was used to simulate the corrosive water-accumulating environment of 7075-T6 aluminum alloy as plane fuel tank material involving microorganisms.Metallographic analysis,electrochemical impedance spectrometry and polarization curve method were employed to investigate the growth curve of sulfate reducing bacteria(denoted as SRB) in the simulated corrosive environment as well as the corroded surface morphology and electrochemical behavior of the Al alloy therein.Results showed that,under a culture temperature of30℃ in the fuel/water system,SRB could adhere and grow on the surface of 7075-T6 alloy,thereby forming a non-uniform biofilm.The corrosion current density of 7075-T6 alloy increased initially and then decreased with extending time,which was in accordance with the variation in the number of SRB.Moreover,S^2-as the metabolite of SRB and the cathodic depolarization action of SRB synergistically functioned to promote the corrosion of 7075-T6 Al alloy in the tested corrosive medium.